Depends on who you are asking because there are some people that will say it's good for currency as well, I mean it has been used as one back when Laszlo bought 2 pizzas right? I think it's a bit of both because Satoshi's aim was to create a currency that will eliminate the middle man which is the banks.
In theory, Bitcoin fills in for both, an asset and a currency. The former is well established and well practiced among many while the latter is less evident because in very few places you can use your currency 'BTC' to pay for goods or services, online there are more options for this but in not many real life.
This often is an implication of the local governments not recognising BTC as more than a digital asset they want to steer way from because of its competition to fiat. It will probably take some time until more governments will take the same approach as El Salvador.